Proper use of dental floss is necessary to clean the considerable area on the interproximal surfaces of teeth, which cannot be reached by the bristles of a toothbrush.
The purpose of dental floss is:
1. to dislodge and remove any decomposing food material that has accumulated at the interproximal surfaces that cannot be removed by brushing, and
2. to dislodge and remove as much as possible the growth of bacterial material (plaque) upon the teeth or the superimposed calculus that has accumulated there since the previous cleaning. Plaque is discussed below.
The concept of the use of dental floss for cleansing interproximal spaces appears to have been introduced by Parmly in 1819. Parmly suggested the use of waxed silk to clean teeth of persons subject to gingival inflammation. Numerous types of floss were developed and used for cleaning, until finally in 1948 Bass established the optimum characteristics of dental floss. (Dental Items of Interest, 1948; 70: 921-34).
Surprisingly, floss marketers have ignored Bass for the past 40 years. Bass warned that dental floss treated with sizing, binders and/or wax produces a "cord" effect which reduces flossing efficiency dramatically. Almost all floss sold today including unwaxed floss contains binders and/or sizing substances. These "sticky" substances are used to keep the floss twists from unwinding during use and to keep the floss turns from falling off a spool during dispensing by holding the floss together. Additionally, most floss sold at retail today is also "waxed" to assist penetration of interproximal regions; as the "cord" effect described by Bass makes the floss bundle difficult to force between closely spaced teeth.
The optimum characteristics of dental floss as described by Bass in 1948 are ignored by today's flosses. Specifically, Bass suggests that these waxed and sized flosses produce the "cord" effect discussed above as distinguished from the "spread effect" of unwaxed, unsized floss which flattens out and widens, with the filaments spread out. The potential for separate mechanical action of spread out filaments is nullified by this "cord" effect, as are the spaces between the filaments, which according to Bass are necessary to receive, hold and remove the microscopic material dislodged during flossing. Thus, the mechanical cleaning attributed to spread filaments and essentially all of the evacuation of microscopic materials from the interproximal spaces by entrapment is impaired or sacrificed with waxed and/or sized flosses, because of this "cord" effect.
As an alternative to sizing, binders, wax etc. Bass suggests "steamset" to set the twist in dental floss so that the floss will not untwist during use. Commercial floss twisters and floss spoolers, opted to use various binders and sizing materials instead. These "sticky" substances facilitate floss handling, keep the floss from untwisting during use, and keep the floss from falling off the spool. Although steamset floss does not untwist during use, absent sticky substances, it does unravel off the spool during dispensing and during spooling. Thus, the optimum floss described by Bass could not be manufactured commercially in 1948, so apparently, water insoluble binders, sizing and wax were adopted early on and continue up to the present.
From 1960 thru 1982, numerous clinical studies reported that there is no clinical difference as to plaque removal and gingivitis scores between waxed and unwaxed dental floss. Note, both are "cord" flosses and contain sizing, binders etc. These studies also confirmed that waxed and unwaxed floss are approximately 50% effective with respect to plaque removal and gingivitis scores. Thus the "cord" effect severely restricts efficiency of flossing.
O'Leary in 1970, and Hill et al in 1973, found no difference in the interproximal cleansing properties of waxed or unwaxed dental floss. This was reconfirmed in 1982 by Lobene et al who showed no significant clinical difference on plaque and gingivitis scores. Similar results, i.e. no clinical difference between waxed and unwaxed floss with respect to reduced gingival inflammation were shown by Finkelstein in 1979. No differences in gingival health were shown by Wunderlich in 1981. No differences in plaque removal were reported by Schmidt et al in 1981 with flosses of various types. Stevens, 1980, studied floss with variable diameters and showed no difference in plaque and gingival health. Carter et al 1975, studied professional and self administered waxed and unwaxed floss, both significantly reduced gingival bleeding of interproximal and gingival sulci. Unwaxed floss appeared slightly, but not significantly more effective.
In view of this clinical work, it is not surprising that most of the dental floss sold today is bonded and/or waxed. The "bonding" in the yarn industry today is used more to facilitate processing and production during floss manufacture and packaging than for "flossing" reasons. Since clinical tests show no difference between waxed and unwaxed floss (both unfortunately are "bonded") the floss industry has been comfortable with the yarn industry's propensity to use bonding agents in floss.
Today there are three basic nylon strand constructions approved by the FDA for flossing. These are 140 denier (68 filament), 100 denier (34 filament), and 70 denier (34 filament). Analysis of the commercial flosses sold worldwide show that almost all flosses available are twisted in generally the same manner, contain bonding agents, and are constructed by twisting several (6-10) strands selected from one of these three strand types.
Almost 100% of the floss sold today is manufactured by "yarn" manufacturers with little consideration given to the influence of twisting of floss construction on cleaning etc.
The simple removal of binders, to allow the floss strands to spread out, introduces a "user-unfriendly" effect which reduces the value Bass described. Commercial flosses with little or no binders are notorious for frustrating flossers with their tendency to fray, break etc. The removal of binders requires adjuncts (lubricants, etc) to reduce snagging, fraying etc.
In view of the foregoing, it is not surprising that shred resistant floss has been the basic claim of some floss marketers. The most recent introduction of a Goretex type floss, with it's monofilament construction, should prove to be the ultimate shred resistant floss. Historically, the typical response to shredding was to develop a "tighter" bonded and smaller diameter floss that did not spread out and did not shred. Waxing was also an option. It is not difficult to see how the "ultimate cord", i.e. monofilament construction, evolved from this approach. The monofilament floss is reported to be easier to use than traditional bonded flosses.
Somehow it has become generally accepted throughout the oral care community today that:
1. the daily mechanical disruption and removal of dental plaque with a standard bonded dental floss is a very effective method of interproximal plaque control. and
2. it would be difficult to demonstrate clinical superiority over the standard commercial flosses.
This conclusion contradicts the mediocre plaque and gingivitis control effect of standard floss as reported consistently in the literature, to wit:
1. The literature has repeatedly documented that gingivitis scores flatten out after 4 weeks of flossing with scores routinely in the 60's. See Lobene et al and other waxed vs unwaxed dental floss studies.
2. Many researchers report that the best floss in the hands of experts will only remove 50 to 60% of the interproximal plaque.
3. Keene in 1974, reported that " . . . ordinary waxed dental floss was neither an efficient debriding agent nor an effective tool for delivery of the test agents to the interproximal sites", and
4. Additionally, Finkelstein and Grossman, Hill et al, Carter et al, Wunderlich et al, Schmid et al, Lamberts et al and Stevens each showed plaque reductions and/or improved gingivitis or improved gingival health with flossing. These results were comparable to Lobene et al, 50 to 60% effective, and leave room for substantial improvement.
There is, therefore a definite need in the art for an improved dental floss, to clean, condition and treat the surfaces flossed.